The two patches here give the ability to people using dav repository to lock/unlock files.

You can use preferences to choose the default timeout for the locking.

You can choose to see or not the remaining time for the lock in the filemanger (choosing the good option in preferences too).

There is a minor modification in phpgwapi to support getting locks depending on people (by default all locks were returned, even if you were not the owner of it, so this was not of a great interrest)
I take the time to clean up the code too in the lock/unlock functions (using the lock_token function).

This should not change anything for sql users until they get the lock system implemented in the vfs_sql layer.

Last but not least,
This patch "depends" heavily from the fixes given previously in my 3 previous patches about dav, So Apply the bugs fixes before applying this one.